Antimycobacterial compounds and method of using same

ABSTRACT

The present invention provides a compound having the structure: ##STR1## wherein R is a branched or unbranched C1-C30 alkyl or alkenyl; or a branched or unbranched C1-C30 alkyl or alkenyl substituted with S, O, N, P, SO 2 , F, C1, Br, or I, wherein S, O, N, P, or SO 2  replaces at least one --CH 2  --, and F, Cl, Br, or I replaces at least one H. The present invention also provides a pharmaceutical composition comprising the compound above, as well as a method for treating a mycobacterial disease or infection in a subject in need of such treatment by administering to the subject an effective amount of the compound above.

STATEMENT OF GOVERNMENT INTEREST

This invention was made with government support under Grant Nos. NIHAI30189 and AI36849. As such, the government has certain rights in thisinvention.

This application is a continuation-in-part of application Ser. No.08/234,011, filed Apr. 28, 1994, and application Ser. No. 08/307,376,filed Sep. 16, 1994, abandoned the contents of which is incorporated byreference herein.

BACKGROUND OF THE INVENTION

Mycobacteria represents major pathogens of man and animals. For example,tuberculosis is generally caused in humans by Mycobacterium (M.)tuberculosis and in cattle by M. bovis (which can be transmitted tohumans to cause tuberculosis). Tuberculosis remains widespread and is animportant public health problem, particularly in developing countries.It is estimated that there are approximately 10 million cases oftuberculosis worldwide, with an annual mortality rate of 3 million.

Cases of disease caused by M. tuberculosis and other mycobacteria suchas M. avium-intracellulare complex (MAC) are increasing as the numbersof immunocompromised individuals is increasing. For example, both M.tuberculosis and M. avium-intracellulare represent major opportunisticpathogens of patients with acquired immunodeficiency syndrome (AIDS).Kochi, A., Governmental Intervention Programs in HIV/TuberculosisInfection: Outline of Guidelines for National Tuberculosis ControlPrograms in View of the HIV Epidemic, Bull Int. Union Tubercul. LungDis. 66: 33-36 (1991).

Current drugs used for controlling mycobacteria other than M.tuberculosis are inadequate. Advisory Group for Opportunistic DiseaseResearch and Education, 1992, Mastering Opportunistic MycobacterialInfections, Parmitalia Carlo Erba, Barnet, Herts, United Kingdom.Furthermore, the recent increase of tuberculosis in the United Stateshas been accompanied by the appearance of drug-resistant strains of M.tuberculosis. Bloom, B. R. and Murray, C. J. L., Tuberculosis:Commentary on a Reemergent Killer, Science 257: 1055-1064 (1992);Snider, D. E. and Roper, W. L., The New Tuberculosis, N. Eng. J. Med.326: 703-705 (1992).

Accordingly, there exists a need for new drugs to combact mycobacteriaand particularly M. tuberculosis and M. avium-intracellulare. Thecompounds of the present invention satisfy this need.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a compoundhaving the structure: ##STR2## wherein R is a branched or unbranchedC1-C30 alkyl or alkenyl; or a branched or unbranched C1-C30 alkyl oralkenyl substituted with S, O, N, P, SO₂, F, Cl, Br, or I, wherein S, O,N, P, or SO₂ replaces at least one --CH₂ --, and F, Cl, Br, or Ireplaces at least one H.

It also is an object of the present invention to provide apharmaceutical composition comprising the compound above and apharmaceutically acceptable carrier.

Lastly, it is an object of the present invention to provide a method fortreating a mycobacterial disease or infection in a subject in need ofsuch treatment which comprises administering to the subject an amount ofthe compound above effective to treat the disease or infection.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1. Schematic diagram of the synthesis of the compounds of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a novel class of "kynoylic acid (KOA)"compounds having the structure: ##STR3## wherein R is a branched orunbranched C1-C30 alkyl or alkenyl; or a branched or unbranched C1-C30alkyl or alkenyl substituted with S, O, N, P, SO₂, F, Cl, Br, or I,wherein S, O, N, P, or SO₂ replaces at least one --CH₂ --, and F, Cl,Br, or I replaces at least one H.

In the preferred embodiment, R is an unbranched C9-C30 alkyl. In themore preferred embodiment, R is a C15 alkyl. This compound has beennamed octadecynoic acid and designated C18KOA (because it contains 18carbon atoms). Compound C18KOA has the following structure: ##STR4##

The compounds of the present invention may be present in the form offree bases or pharmaceutically acceptable acid addition salts thereof.Examples of suitable acids for salt formation are: methanesulfonic,sulfuric, hydrochloric, phosphoric, acetic, citric, lactic, ascorbic,maleic, and the like.

The present invention also provides a pharmaceutical compositioncomprising one or more of the compounds above and a pharmaceuticallyacceptable carrier. The carrier must be "acceptable" in the sense ofbeing compatible with the other ingredients of the formulation and notdeleterious to the recipient thereof. The compound may be formulatedwith one or more pharmaceutically acceptable diluents or carriers, andoptionally, any other ingredients which may be therapeutic per se,and/or may be synergistic with the compounds of the present invention.These include chemotherapeutic agents known to act against theparticular mycobacterial species (e.g. for M. tuberculosis, thesecompounds may include isoniazid, ethionamide, rifampicin and/orpyrazinamide). The concentration of the compound present in theformulation will depend upon the choice of carrier as well as theresults desired.

Examples of suitable pharmaceutical carriers include lactose, sucrose,starch, talc, magnesium stearate, crystalline cellulose, methylcellulose, carboxymethyl cellulose, glycerin, sodium alginate, gumarabic, powders, saline, water, among others. The choice of carrier willdepend upon the route of administration. The formulations mayconveniently be presented in unit dosage and may be prepared by methodswell-known in the pharmaceutical art, by bringing the active compoundinto association with a carrier or diluent, as a suspension or solution,and optionally one or more accessory ingredients, e.g. buffers,flavoring agents, surface active agents, and the like.

For intravenous, intramuscular, subcutaneous, or intraperitonealadministration, the compound is combined with a sterile aqueous solutionwhich is preferably isotonic with the blood of the recipient. Suchformulations may be prepared by dissolving solid active ingredient inwater containing physiologically compatible substances such as sodiumchloride, glycine, and the like, and having a buffered pH compatiblewith physiological conditions to produce an aqueous solution, andrendering said solution sterile. The formulations may be present in unitor multi-dose containers such as sealed ampoules or vials.

For oral administration, the formulation may be presented as capsules,tablets, powders, granules or a suspension, with conventional additivessuch as lactose, mannitol, corn starch or potato starch; with binderssuch as crystalline cellulose, cellulose derivatives, acacia, cornstarch or gelatins; with disintegrators such as corn starch, potatostarch or sodium carboxymethyl-cellulose; and with lubricants such astalc or magnesium stearate.

Formulations suitable for parenteral administration convenientlycomprise a sterile aqueous preparation of the active compound which ispreferably made isotonic. Preparations for injections may also beformulated by suspending or emulsifying the compounds in non-aqueoussolvent, such as vegetable oil, synthetic aliphatic acid glycerides,esters of higher aliphatic acids or propylene glycol.

The present invention further provides a method for treating amycobacterial disease or infection in a subject in need of suchtreatment which comprises administering to the subject an amount of thecompound above effective to treat the mycobacterial disease orinfection.

The term "treatment" includes the partial or total inhibition ofmycobacterial disease or infection. The term "subject" includes a humanor animal subject diagnosed as having the mycobacterial disease orinfection. In the preferred embodiment, the mycobacterial disease is M.tuberculosis or M. avium, and most preferably is M. tuberculosis.

The administration may be affected by means known to those skilled inthe art such as oral, rectal, topical, intravenous, subcutaneous,intramuscular, or intraperitoneal routes of administration.

The dosage form and amount can be readily established by reference toknown chemotherapeutic treatments of mycobacterial diseases orinfections. In general, however, the dosage of the compound will bewithin the range of about 0.01 μg/kg to about 100 mg/kg, and preferablybetween about 1 μg/kg and about 10 mg/kg. The actual dose will dependupon the route of administration, the pharmacokinetic properties of theindividual treated, as well as the results desired.

The present invention is described in the following examples which areset forth to aid in the understanding of the invention, and should notbe construed to limit in any way the invention as defined in the claimswhich follow thereafter.

EXAMPLE 1 Preparation of Compounds

The scheme for preparing the compounds of the present invention isoutlined in FIG. 1. A detailed description of the synthesis of thesecompounds is as follows:

A. 1-Bromoalkanes

To a suspension of 1-hydroxyalkane (6.1 mmol) in dry ether (15 mL) wasadded, under nitrogen, phosphorus tribromide (580 mL, 6.1 mmol). Thewhite suspension was heated at reflux for 3 h, and then stirred at roomtemperature overnight. The reaction mixture was quenched by addition ofa saturated solution of sodium bicarbonate at 0° C. After the mixturewas stirred for 30 min, the ether phase was separated, dried over sodiumsulfate, filtered, evaporated under vacuum, and filtered through a padof silica gel (elution with hexane) to give the 1-bromoalkane.

B. 1-Alkynes

A suspension of lithium acetylide ethylene-diamine complex (412 mg, 4.5mmol) in dry dimethyl sulfoxide (2.2 mL) was stirred for 10 min at roomtemperature under nitrogen. After cooling to 8° C., 1-bromoalkane (4.1mmol) was added dropwise (if the bromoalkane is a solid, it issolubilized first in tetrahydrofuran). The reaction mixture was stirredat room temperature for 4 h, and cooled to 0° C. Water (1 mL) was addedvery slowly. The suspension was stirred for 10 min at room temperature,then poured into water (60 mL), and extracted with hexane. The combinedorganic phases were dried over sodium sulfate, filtered, evaporatedunder vacuum, purified by filtration through a small pad of silica gel,eluted with hexane, and analyzed by ¹ H and ¹³ C NMR.

C. 2-Alkynoic Acids

To a solution of 1-alkyne (1.63 mmol) in dry THF (6.5 mL), at -23° C.,was added n-butyllithium (2.5M solution in hexanes, 0.69 mL, 1.73 mmol)under nitrogen. The solution was stirred for 1 h, cooled to -50° C., andthen poured into a slurry of dry ice (3 g)/dry ether (3 mL). Thereaction mixture was stirred at room temperature overnight, poured into3 N HCl, and extracted with ether. The combined organic phases weredried over sodium sulfate, filtered, evaporated under vacuum, andpurified by flash chromatography (elution with hexane/ethylacetate/glacial acetic acid 80/20/1).

EXAMPLE 2 Testing of Compounds

The CDC indirect proportion method of suseptibility testing was used toevaluate the activity of compounds C18KOA and C20KOA against M.tuberculosis. This method was performed with a bacterial suspension madefrom a fresh 7H9 broth culture. A suspension was adjusted to the opticaldensity of a MacFarland Standard No. 1, and two dilutions of thissuspension, 10⁻³ and 10⁻⁴, were then used to inoculate two separate setsof 7H10/OADC quadrant plates, one for each drug. Drug-free medium wasplaced in one quadrant of each set. The three other quadrants containedthe drugs. For each respective dilution inoculum, three drops wereplaced in each quadrant, and the plates were incubated for two weeks at37° C. in an atmosphere of 10% CO2. Plates were then read and thepercentage of resistant bacteria in the population (1% or greater isdefined as resistant) was reported on the basis of comparison of thenumber of colony-forming units (CFU) on the drug containing anddrug-free quadrants found in the two sets of plates.

For the KOA compounds tested, four sets of plates were made whichcontained 0, 1, 10 and 100 μg/ml of either C18KOA or C20KOA. Definedbacterial suspensions of two M. tuberculosis strains (one is isoniazidsusceptible and one is resistant) were inoculated on the plates, and theplates were incubated as described above. After two weeks, 100 to 200CFU appeared on both M. tuberculosis strains on the C18KOA 0 and 1 μg/mltreated quadrants, but no CFU appeared on both M. tuberculosis strainson the 10 and 100 μg/ml quadrants. For C20KOA, 100 to 200 CFU appearedon both M. tuberculosis strains on the 0, 1, and 10 μg/ml treatedquadrants, but no CFU appeared on both M. tuberculosis strains on the100 μg/ml quadrant.

In summary, C18KOA shows inhibitory antituberculosis activity of 10μg/ml against isoniazid susceptible and resistant strains of M.tuberculosis; and C20KOA show inhibitory antituberculosis activity at100 μg/ml against the same strains.

All publications mentioned hereinabove are hereby incorporated in theirentirety.

While the foregoing invention has been described in some detail forpurposes of clarity and understanding, it will be appreciated by oneskilled in the art from a reading of the disclosure that various changesin form and detail can be made without departing from the true scope ofthe invention in the appended claims.

What is claimed is:
 1. A method for treating M. tuberculosis infectionin a subject in need of such treatment which comprises administering tothe subject an effective amount of a compound having the structure:RC.tbd.CCO₂ H, wherein R is an unbranched C9-C30 alkyl, to treat M.tuberculosis infection in the subject.
 2. The method of claim 1, whereinR is a C15 alkyl.